ASP.net 4 with Visual Web Developer Express 2010

ASP.net 4 with Visual web developer express 2010.
I am querying a database to add items to a gridview based on session parameters. It just returns the default. Where am I going wrong?
Any suggestions would be much appreciated.
Here is the code(with connection details changed):
<form id="Form1" method="post" runat="server">
<p>Show My Orders:</p>

Thanks for your quick response Brett.
Actually 'cast' was a typo when I was typing the question. It is
actually 'cart'

This is the routine which fill the session data and it does contain the
ProductID's taken from the gridview which displays the products.
Protected Sub GridView1_RowCommand(sender As Object, e As
System.Web.UI.WebControls.GridViewCommandEventArgs ) Handles
GridView1.RowCommand
If (e.CommandName = "AddToCart") Then
Dim RowClicked As Integer = Convert.ToInt32(e.CommandArgument)
Dim ProductID As Integer =
Convert.ToInt32(GridView1.DataKeys(RowClicked).Val ue)
Dim ProductsInCart As List(Of Integer) =
DirectCast(Session("Cart"), List(Of Integer))
If (ProductsInCart Is Nothing) Then
ProductsInCart = New List(Of Integer)()

End If
ProductsInCart.Add(ProductID)
Session("Cart") = ProductsInCart
End If
End Sub